Synthesis and Characterization of Osmium-Containing Silsesquioxanes:  High-Yield Routes to {Os₃(CO)₁₀(μ-H)[(μ-O)Si₇O₁₀(c-C₆H₁₁)₇]} and the New Clusters {Os₃(CO)₁₀(μ-H)[(μ-O)Si₇O₉(OH)₂(c-C₆H₁₁)₇]}, {[Os₃(CO)₁₀(μ-H)]₂(μ-O)₂Si₇O₉(OH)(c-C₆H₁₁

Abstract

The reactions of [Os 3 (CO) 10 (µ-H)(µ-OH)] (3) with the incompletely condensed silsesquioxanes [(c-C 6 H 11 ) 7 Si 7 O 9 (OH) 3 ] (1) and [(c-C 6 H 11 ) 8 Si 8 O 11 (OH) 2 ] (2) afford in high yield {Os 3 (CO) 10 (µ-H)[(µ-O)-Si 7 O 10 (c-C 6 H 11 ) 7 ]} (4) and the new compounds {Os 3 (CO) 10 (µ-H)[(µ-O)Si 7 O 9 (OH) 2 (c-C 6 H 11 ) 7 ]} (5), {[Os 3 (CO) 10 (µ-H)] 2 (µ-O) 2 Si 7 O 9 (OH)(c-C 6 H 11 ) 7 } (6), {Os 3 (CO) 10 (µ-H)[(µ-O)Si 8 O 11 (OH)(c-C 6 H 11 ) 8 ]} (8), and {[Os 3 (CO) 10 (µ-H)] 2 (µ-O) 2 Si 8 O 11 (c-C 6 H 11 ) 8 } (9), which are discrete molecular models of silica-anchored [Os 3 (CO) 10 (µ-H)(µ-OSit)]. Compounds 6 and 9 represent the first examples of complexes containing two [Os 3 (CO) 10 (µ-H)] cluster cores. The X-ray structures of 5, 8, and 9 are reported.

Synthesis and Characterization of Platinasilsesquioxane Complexes and Their Reaction with Arylboronic Acid

“…The respective 31 P− 195 Pt coupling constants fall in the typical range of the phosphine ligands bonded at trans positions of an aryl ligand and of an O -ligand in Pt(II) complexes. ,− Both complexes show 29 Si{ 1 H} NMR spectra that consist of five signals in 1:2:1:1:2 ratio. These signals are typical for the silsesquioxane framework with C s symmetry and often observed in the spectrum of transition metal complexes having a monodentate silsesquioxanate ligand. ,, 13 C{ 1 H} NMR signals with the same intensity are observed in the range 22.5−26.6 ppm and are assigned to the CH carbons of the cyclopentyl groups.…”

Synthesis, reactivity and X-ray crystal structure of tris(pentafluorophenyl)silanol (C6F5)3SiOH

“…The investigation on the structure and reactivity of silica-anchored organometallic species has been improved in the last two decades also through the complementary investigation on the synthesis, structure and reactivity of molecular models bearing silanolate ligands which mimic the silanol groups of the silica surface [1][2][3][4][5][6][7]. For instance, some of us reported evidence for the peculiar stabilization of the rhenium pentacarbonyl species [Re(CO) 5 OSi≡] on the silica surface, but the synthesis of its molecular model [Re(CO) 5 OSiR 3 ] was hampered by the fact that nucleophiles, such as Me 3 SiO -, are exceptionally good cis-labilizing ligands that facilitate the instantaneous loss of carbonyl ligands and further nucleophilic attacks to give dimeric units bridged by silanolate groups such as [Re 2 (CO) 6 (-OSiMe 3 ) 3 ] - [8]. The use of a silanolate anion with much lower nucleophilicity, such as the silsesquioxane derivative (c-C 6 H 11 ) 7 Si 8 O 12 O -, enabled some of us to synthesize and spectroscopically characterize the surface model species [Re(CO) 5 OR] (R=(c-C 6 H 11 ) 7 Si 8 O 12 ), stable only under CO atmosphere and at 273 K [9].…”

“…For instance, some of us reported evidence for the peculiar stabilization of the rhenium pentacarbonyl species [Re(CO) 5 OSi≡] on the silica surface, but the synthesis of its molecular model [Re(CO) 5 OSiR 3 ] was hampered by the fact that nucleophiles, such as Me 3 SiO -, are exceptionally good cis-labilizing ligands that facilitate the instantaneous loss of carbonyl ligands and further nucleophilic attacks to give dimeric units bridged by silanolate groups such as [Re 2 (CO) 6 (-OSiMe 3 ) 3 ] - [8]. The use of a silanolate anion with much lower nucleophilicity, such as the silsesquioxane derivative (c-C 6 H 11 ) 7 Si 8 O 12 O -, enabled some of us to synthesize and spectroscopically characterize the surface model species [Re(CO) 5 OR] (R=(c-C 6 H 11 ) 7 Si 8 O 12 ), stable only under CO atmosphere and at 273 K [9]. In order to obtain a different ligand characterized by a similar very poor nucleophilicity, suitable to afford a stable [Re(CO) 5 OSiR 3 ] species by reaction with rhenium pentacarbonyl complexes, we investigated the synthesis and reactivity of (C 6 F 5 ) 3 SiOH.…”

“…The use of a silanolate anion with much lower nucleophilicity, such as the silsesquioxane derivative (c-C 6 H 11 ) 7 Si 8 O 12 O -, enabled some of us to synthesize and spectroscopically characterize the surface model species [Re(CO) 5 OR] (R=(c-C 6 H 11 ) 7 Si 8 O 12 ), stable only under CO atmosphere and at 273 K [9]. In order to obtain a different ligand characterized by a similar very poor nucleophilicity, suitable to afford a stable [Re(CO) 5 OSiR 3 ] species by reaction with rhenium pentacarbonyl complexes, we investigated the synthesis and reactivity of (C 6 F 5 ) 3 SiOH. To our knowledge in the literature (C 6 F 5 ) 3 SiOH has been previously briefly mentioned in a communication on the reactivity of (C 6 F 5 ) 3 SiCl with water [10], and in a patent for the preparation of polyene compounds obtained in the presence of siloxy-vanadium catalysts of general formula (R 3 SiO) m (OR') n VO (R = phenyl with one or more electron-withdrawing substituents; R' = alkyl, cycloalkyl, Ph, Ph 3 Si, etc.…”

Synthesis, Spectroscopic, and X-ray Characterization of Rhenium Carbonyl Complexes with Different Silsesquioxanes, as Models That Mimic the Chemical Behavior and the Topology of the Silica Surface

“…Although models of silica-anchored carbonyl species of various noble metals (for example Rh, Os, , and Ru) have been thoroughly investigated, much less is known about models involving oxophilic metals such as rhenium, , despite the industrial relevance of catalysts based on rhenium supported on inorganic oxides for reactions such as olefin metathesis, epoxidation, hydrogenation, dehydrogenation, and petroleum refining…”